Pallet dismantler

ABSTRACT

A method for dismantling pallets includes hanging a pallet on the upstream end of a cantilevered support having a substantially horizontal top surface with the bottom surfaces of the upper deck boards of the pallet resting on the top surface of the cantilevered support and with the stringer boards and lower deck boards extending downwardly from the top surface, advancing the hanging pallet in a downstream direction along the cantilevered support toward a band saw blade which lies directly on the top surface of the cantilevered support and defines a cutting plane aligned with the top surface of the cantilevered support, thereby automatically aligning the band saw blade with the pallet joints between the upper deck boards and the stringer boards; and advancing the pallet past the band saw blade to separate the upper deck boards from the stringer boards at the pallet joints.

This application is a divisional of U.S. patent application Ser. No.11/688,661, filed Mar. 20, 2007.

BACKGROUND

The present invention relates to saws, and, in particular, to a saw fordismantling pallets. A pallet is a support structure typicallyconstructed from wooden boards fastened together to form a frameworkthat is useful for shipping and/or storing materials. Generally, thestandard pallet includes upper and lower sets of deck boards, which arenailed or stapled to a set of stringer boards between the upper andlower sets of deck boards. The bottom surfaces of the upper deck boardsand the top surfaces of the lower deck boards abut the stringer boardsat pallet joints. The deck boards lie parallel to each other and usuallyare 40 inches long. The stringer boards lie parallel to each other andperpendicular to the deck boards and usually are 48 inches long. Oncethe pallets have been used, it often is desirable to dismantle them,separating the boards from each other at the pallet joints so they canbe handled easily. In prior art pallet dismantling saws, there typicallyhas been a problem getting the saw blade aligned with the pallet so itcuts exactly at the intersection of the deck boards with the stringerboards (at the pallet joints) in order to cut through the fasteners,such as nails or staples, while leaving the boards intact.

Many complex arrangements have been used in the past to try to providethe desired alignment between the saw blade and the pallet joint. Forexample, U.S. Pat. No. 6,128,992 “Waechter et al.” provides a verycomplex arrangement including two large, swinging band saw structuresthat hang from the ceiling. This arrangement is expensive and isdifficult to install and to maintain.

SUMMARY

The present invention automatically aligns the band saw blade with thepallet joint by suspending the pallet from a cantilevered support, withthe bottom surface of the deck board of the pallet resting on the topsurface of the cantilevered support and with the band saw blade lyingdirectly on the top surface of the cantilevered support. While thisarrangement is very unorthodox, especially in that it goes against theconventional teachings in the art by scrubbing the side of the band sawblade along the surface of the table that supports the workpiece, itsolves the problem of aligning the band saw blade with the pallet jointand is simple and easy to maintain, overcoming the need for the complexsolutions of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an upstream perspective view of one embodiment of a palletdismantler made in accordance with the present invention;

FIG. 1A is a top view of the pallet dismantler of FIG. 1, with the feedconveyor removed for clarity;

FIG. 2 is a downstream perspective view of the pallet dismantler of FIG.1, shown with a pallet loaded;

FIG. 2A is an enlarged view of the portion 2A of FIG. 2;

FIG. 3 is an upstream view of the pallet dismantler of FIG. 1, shownwith a pallet loaded;

FIG. 4 is a right side view of the pallet dismantler of FIG. 1, shownwith a pallet loaded;

FIG. 5 is a top view of the pallet dismantler of FIG. 1, shown in afirst stage of dismantling a pallet;

FIG. 5A is a side sectional view taken along line 5A-5A of FIG. 5;

FIG. 5B is an enlarged view of the portion 5B of FIG. 5A;

FIG. 6 is a top view of the pallet dismantler of FIG. 1, shown in asecond stage of dismantling a pallet;

FIG. 6A is a side sectional view taken along line 6A-6A of FIG. 6;

FIG. 7 is a top view of the pallet dismantler of FIG. 1, shown in athird stage of dismantling a pallet; and

FIG. 7A is a side sectional view taken along line 7A-7A of FIG. 7.

DETAILED DESCRIPTION

FIGS. 1-7A show one embodiment of a pallet dismantler 10 made inaccordance with the present invention. The basic components of thepallet dismantler 10 include a support frame 20 having an upstream end22, a downstream end 24, left side 26, and right side 28. Elongated,parallel cantilevered supports 30 are supported at the downstream end 24of the frame 20 and project to the upstream end 22. These cantileveredsupports 30 are arranged like fork tines, with spaces between the tines30. A band saw 35 is mounted between the upstream and downstream ends22, 24 and has a saw blade 40 extending across the top of thecantilevered supports 30 from the left side 26 to the right side 28. Thecantilevered supports 30 extend in a horizontal direction, and their topsurfaces define a horizontal plane.

The band saw blade 40 rotates at a high speed. It extends tightly aroundtires mounted on left and right wheels 42, 44 (shown in FIGS. 1 and 3),which are driven by a motor 46 that engages the left wheel 42 (bestshown in FIG. 5), as is commonly known in the art. In this case, theband saw blade 40 lies directly on top of the cantilevered supports 30and thus defines a horizontal cutting plane that is aligned with thehorizontal plane defined by the top surfaces of the cantileveredsupports 30. When the band saw 35 is turned on, the blade 40 rotates ina counterclockwise direction (as viewed from the upstream end of thepallet dismantler 10) so that the band saw blade 40 moves from right toleft through the cutting plane as denoted by the arrow 48 in FIG. 3. Thehigh-speed rotation of the band saw blade 40 is used to sever thefasteners of a pallet in order to separate the boards, as will beexplained in greater detail later.

As best shown in FIG. 1A, each cantilevered support 30 has a downstreamend 34 near the downstream end 24 of the frame 20 and extends past theband saw blade 40 to an upstream end 32 near the upstream end 22 of theframe 20. As shown in FIG. 2, the cantilevered supports 30 are mountedon a cross-beam 25 at the downstream end 24 of the frame 20 and then areunsupported or cantilevered as they project upstream from the cross-beam25 to their free ends 32.

In this embodiment, there are six cantilevered supports 30, with spacesdefined between the supports 30, and the upstream ends 32 of thecantilevered supports 30 are upstream of the band saw blade 40 adistance of 52 inches, which is slightly greater than the 48-inch lengthof a standard pallet 50 (the length of the stringer boards 56), as bestshown in FIGS. 5 and 5A. While it is preferred for the cantileveredsupports 30 to extend upstream of the band saw blade 40 the full lengthof the pallet stringers 56 in order to provide good support for thepallet as it is being fed into the saw blade 40, the cantileveredsupports 30 should extend upstream of the saw blade 40 at least half thelength of the stringer boards 56, or at least two feet, so the palletsdo not tilt off of the horizontal plane defined by the cantileveredsupports 30 as they are fed into the cutting blade 40.

Also, in this embodiment, the unsupported distance over which thecantilevered supports 30 project from the cross-beam 25 upstream to theband saw blade 40 is 52 inches, which again is slightly greater than thelength of the stringer boards 56. The supports 30 should be cantileveredfrom the cross-beam 25 to the saw blade 40 at least the length of thepallet (the length of the stringer boards 56) in order to preventinterference between the remainder of the pallet and the supportstructure as the partially dismantled pallet progresses downstream pastthe cutting blade 40.

Since the cantilevered supports 30 generally will be cantilevered fromthe support structure to the saw blade 40 a distance slightly greaterthan the length of the pallet, and since they should continue to becantilevered a distance upstream of the saw blade 40 at least half thelength of the pallet in order to provide good support for the pallet asit is being fed into the saw blade 40, the cantilevered supports 30typically will extend upstream of the saw blade 40 at least half of thedistance that they are cantilevered (unsupported) downstream of the sawblade 40, and, for better support, they usually will extend upstreamfrom the saw blade 40 about the same distance that they are cantilevereddownstream of the saw blade 40. In other words, the length of thecantilevered supports 30 in the downstream direction from the upstreamfree end 32 to the band saw blade 40 is at least half of the length ofthe cantilevered supports in the downstream direction from the band sawblade 40 to the downstream end 34. In other embodiments, there could bemore or fewer cantilevered supports.

While the pallets 50 could be fed through the saw by hand, this palletdismantler 10 also includes a feed conveyor 60 extending parallel to andabove the cantilevered supports 30 for feeding the pallet 50 through thesaw. As best shown in FIGS. 5A and 5B, the feed conveyor 60 includespropelling elements 62 that engage a pallet 50 resting on thecantilevered supports 30 and propel it downstream through the palletdismantler 10. In this embodiment, the feed conveyor 60 includes threeseparate and parallel chains 64 driven by sprockets 65 sharing the samefront and rear axles 66, 68. Each chain 64 has a plurality of evenlyspaced and aligned projections 62, which function as propellingelements, contacting the deck boards of the pallet and dragging itdownstream along the cantilevered supports 30. Each projection 62 has aflat forward surface 62B for contacting the rear edge of the deck boardsand a pointed end 62C for contacting the top surface of the deck boards.The projections 62 are short enough that they will not interfere withthe saw blade.

Underneath the cantilevered supports 30 are two return conveyors 70,which, in this embodiment, are belt conveyors. While the remainder ofthe pallets 50 could be returned manually, the return conveyors 70collect the remainder of the pallet 50 that falls during the dismantlingprocess and return the remainder to the upstream end 22 of the palletdismantler 10. The two return conveyors 70 operate parallel to eachother and at the same speed. Of course, the pair of return conveyorscould be replaced by a single return conveyor.

The pallet dismantler 10 also includes a guide rail 80 positioned on theleft side 26 of the frame 20 parallel to the cantilevered supports 30.The guide rail 80 defines a vertical abutment surface 82 for receivingand guiding the left side of a pallet 50 as it is fed past the band sawblade 40. Since the band saw blade 40 moves through the cutting plane ina right to left direction, it has a natural tendency to thrust theobject it is cutting to the left. Thus, the guide rail 80 is positionedon the left side 26 of the frame 20 to provide a stop for the pallet 50as it is cut by the band saw blade 40. In addition, the band saw blade40 in this embodiment is angled slightly off of perpendicular to thecantilevered supports 30 and to the direction of travel of the pallet50, which is in the direction of the cantilevered supports 30. As bestshown in FIGS. 5, 6 and 7, the portion of the band saw blade 40 near theleft side 26 of the frame 20 is slightly downstream from its positionnear the right side 28 of the frame 20. By angling the band saw blade 40relative to the direction of travel of the pallet 50, the right side ofthe pallet 50 is cut by the band saw blade 40 slightly ahead of the leftside of the pallet 50. This facilitates feeding the pallet 50 into thesaw blade 40, so that only a portion of the pallet 50 contacts the sawblade 40 at first, and then the rest of the front edge of the pallet 50is gradually fed into the saw blade 40.

FIGS. 2, 2A, 3 and 4 are views of the pallet dismantler 10 with a pallet50 loaded onto the cantilevered supports 30 and ready for dismantling.The pallet 50 is a standard stringer-style pallet 50 having a set ofupper deck boards 52, a set of lower deck boards 54, and a set ofstringer boards 56 secured perpendicularly between the upper and lowersets of deck boards 52, 54. The upper and lower sets of deck boards 52,54 typically are secured to the stringer boards with nails, staples, orsimilar fasteners. In this case, there are twelve upper deck boards 52,three lower deck boards 54, and three stringer boards. Of course, thenumber of boards may vary. As was explained earlier, a typical pallet 50has stringer boards 56 that are four feet long and deck boards 52 thatare 40 inches long. The pallet 50 has been loaded manually onto thecantilevered supports 30, being slid onto the free, upstream end 32 ofthe supports, such that it hangs from the horizontal cantileveredsupports 30, with the bottom surfaces of the upper deck boards 52resting on the top surface of the cantilevered supports 30 and the restof the pallet 50 (the stringer boards 56 and lower deck boards 54)extending downwardly from the top surface.

As best shown in FIG. 3, when the pallet 50 is hung from thecantilevered supports 30, the stringer boards 56A, 56B extend downwardlyfrom the upper deck boards 52 past the cantilevered supports 30, withthe two outer stringer boards 56A positioned on the outside of thecantilevered supports 30 and the middle stringer board 56B positioned inone of the spaces between a pair of adjacent, internal cantileveredsupports 30. The set of lower deck boards 54, which is secured to thebottom of the stringer boards 56, is positioned beneath the cantileveredsupports 30. Thus, the height of the cantilevered supports 30 is lessthan the height of the stringer boards 56, so the cantilevered supports30 fit between the upper and lower sets of deck boards 52, 54 of astandard pallet. Further, the cantilevered supports 30 are relativelynarrow, leaving sizable spaces between the supports 30 so that palletswith various configurations of stringer boards can fit between thecantilevered supports 30. In this particular embodiment, thecantilevered supports 30 are 2.5 inches high, 1.25 inches wide, and arespaced apart on 6 inch centers.

Since the band saw blade 40, which lies directly on the top surfaces ofthe cantilevered supports, is substantially aligned with the topsurfaces of the cantilevered supports 30, and the bottom surfaces of theupper deck boards 52 rest on the top surface of the cantileveredsupports 30, the band saw blade 40 is automatically aligned with thepallet joints between the upper deck boards 52 and the stringer boards56 when the pallet 50 is hung from the cantilevered supports 30. As thepallet 50 is advanced toward the band saw blade 40, the band saw blade40 cuts the pallet 50 at the joint between the upper deck boards 52 andthe stringer boards 56, cutting through the nails or staples 57, withoutdamaging the boards, as best shown in FIG. 2A. Thus, the palletdismantler 10 is designed to cut through the fasteners that secure theupper deck boards 52 to the stringer boards 56, separating the upperdeck boards 52 from the stringer boards 56, while leaving the boards 52,56 intact. Of course, due to inconsistencies in individual pallets, suchas the inconsistencies that may result from warped boards, the band sawblade 40 may cut slightly into the boards in some cases. However, inmost instances, the upper deck boards 52 and stringer boards 56 remainessentially intact.

FIGS. 5, 5A, 5B, 6, 6A, 7, and 7A show the pallet 50 at various stagesin the dismantling process. In FIGS. 5 and 5A, the band saw blade 40 hasjust started cutting through the pallet 50. The pallet 50 has beenadvanced a short distance from the free end of the cantilevered support30 by the feed conveyor 60 via the propelling elements 62 contacting theupper deck boards 52 as the chains 64 of the feed conveyor 60 are drivenby the sprockets 65, conveying the pallet 50 from the upstream end 22 ofthe frame toward the downstream end 24.

FIGS. 6 and 6A show an intermediate stage in the dismantling process. Atthis stage, the band saw blade 40 has separated all of the upper deckboards 52 from the stringer boards 56. The pallet remainder, which is acombination of stringer boards 56 and lower deck boards 54 (which arestill fastened together), has fallen onto the return conveyors 70, andthe upper deck boards 52 continue to be advanced toward the downstreamend 24 of the frame 20 by the feed conveyor 60, where they fall off theend and are collected in a downstream hopper 74 (shown in FIG. 7A).

It should be noted that, while the return conveyors 70 have been shownhere as being a substantial distance below the cantilevered supports 30and being oriented horizontally, the height of the return conveyors 70is adjustable. In practice, the return conveyors 70 typically would beadjusted so they would be higher at the point where they catch thepallet remainders and would be lower at the upstream end of theconveyor. It is preferable that the point where the return conveyor 70catches the pallet remainder be just slightly lower than the bottom ofthe stringers 56 and lower deck boards 54 it is catching in order toprevent the falling stringers 56 and lower deck boards 54 from shiftingdownwardly a great enough distance to cause the rear of the pallet totip upwardly, out of proper alignment with the saw blade. Alternatively,instead of a return conveyor 70, an angled catch pan may be used. Inthat case, the portion of the catch pan that catches the palletremainder would be at a high enough elevation to prevent the fallingstringers 56 from falling far enough to cause the rear of the pallet totip upwardly out of alignment with the blade, and the catch pan would beangled downwardly in the upstream direction so the pallet remainderslides down the catch pan to the upstream end of the saw.

FIGS. 7 and 7A show a subsequent stage of the dismantling process. Atthis point, the upper deck boards 52 have reached the downstream end 24of the frame, with several of the upper deck boards 52 falling into thedownstream hopper 74. As the dismantling process continues, the upperdeck boards 52 accumulate in the downstream hopper 74. Also at thispoint, the remaining combination of lower deck boards 54 and stringerboards 56 (still secured together) has advanced close to the upstreamend 22 of the saw via the return conveyors 70.

In the next stage of dismantling, an operator standing at the upstreamend 22 of the saw 10 typically removes the remaining combination oflower deck boards 54 and stringer boards 56 from the return conveyor 70and feeds it back into the pallet dismantler 10, this time with the setof lower deck boards 54 resting on the cantilevered supports 30 and thestringer boards 56 extending downwardly past the cantilevered supports30. As this pallet remainder is fed past the band saw blade 40, thestringer boards 56 are separated from the lower deck boards 54, with theset of lower deck boards 54 falling into the downstream hopper 74 andthe stringer boards 56 falling onto the return conveyor 70 and returningto the upstream end 22, where they fall into an upstream hopper 72(shown in FIG. 7A). The result is that the upper and lower deck boards52, 54 are collected in the downstream hopper 74, and the stringerboards 56 are collected in the upstream hopper 72.

It will be obvious to those skilled in the art that modifications may bemade to the embodiment described above without departing from the scopeof the invention as claimed.

1. A method for dismantling a standard pallet having upper and lower sets of deck boards and a set of stringer boards between said upper and lower sets of deck boards, with the bottom surfaces of the upper deck boards and the top surfaces of the lower deck boards abutting the stringer boards at pallet joints, comprising the steps of: hanging the pallet on the upstream end of a cantilevered support having a substantially horizontal top surface with the bottom surfaces of the upper deck boards resting on the top surface of the cantilevered support and with the stringer boards and lower deck boards extending downwardly from the top surface of the cantilevered support; advancing the hanging pallet in a downstream direction along the cantilevered support toward a band saw blade which lies directly on the top surface of the cantilevered support and defines a cutting plane aligned with the top surface of the cantilevered support, thereby automatically aligning the band saw blade with the pallet joints between the upper deck boards and the stringer boards; and advancing the pallet past the band saw blade to separate the upper deck boards from the stringer boards at the pallet joints, forming a pallet remainder.
 2. A method for dismantling a pallet as recited in claim 1, and further comprising the steps of: turning over the pallet remainder and hanging it from the cantilevered support with the lower deck boards resting on the top surface of the cantilevered support and the stringer boards extending downwardly from the top surface of the cantilevered support; and advancing the pallet remainder past the band saw blade to separate the lower deck boards from the stringer boards at the pallet joints between the lower deck boards and the stringer boards.
 3. A method for dismantling a pallet as recited in claim 2, wherein the step of advancing the pallet includes contacting the deck boards with a driven propelling element.
 4. A method for dismantling a pallet as recited in claim 1, and further comprising the step of returning the pallet remainder to the upstream end by means of a return conveyor.
 5. A method for dismantling a pallet as recited in claim 1, wherein the cantilevered support extends from a downstream end to the upstream end, and the length of said cantilevered support in the downstream direction from said upstream end to said band saw blade is at least half of the length in the downstream direction from said band saw blade to said downstream end.
 6. A method for dismantling a pallet as recited in claim 1, wherein the cantilevered support includes a plurality of spaced-apart tines, and wherein at least one of the stringer boards passes through a space between the tines as the pallet advances toward the saw blade. 